Manually-operable multi-well microfiltration apparatus and method

ABSTRACT

A multi-well microfiltration apparatus and method are provided and feature a manual touch-off system for transferring pendent drops hanging from discharge-conduits of a discharge-conduit array to respective receiving wells or receiving holes of a corresponding receiving array, with minimum or no cross-contamination between the discharge conduits, or the receiving wells or receiving holes. The manual touch-off is achieved by manually shifting a carriage that supports one of the arrays, into a position whereat pendent drops of fluid hanging from the distal ends of the discharge conduits contact the inner sidewalls of the corresponding receiving wells or receiving holes of the receiving array.

This application is a Continuation of U.S. application Ser. No.11/120,797, filed May 3, 2005, which in turn is a Continuation of U.S.application Ser. No. 10/359,665, filed Feb. 6, 2003, which in turn is aContinuation-In-Part of U.S. application Ser. No. 10/104,335, filed Mar.22, 2002, now U.S. Pat. No. 6,896,849 B2, issued May 24, 2005, whichin-turn is a Continuation-In-Part of U.S. application Ser. No.09/552,301, filed Apr. 18, 2000, now U.S. Pat. No. 6,419,827 B1, issuedJul. 16, 2002, which in-turn is a Continuation-In-Part of U.S.application Ser. No. 09/182,946, filed Oct. 29, 1998, now U.S. Pat. No.6,159,368, issued Dec. 12, 2000, both the applications and the patentsbeing incorporated herein, in their entireties, by reference.

FIELD OF THE INVENTION

The present invention relates to multi-well microfiltration apparatusand methods for processing a plurality of fluid samples simultaneously.The present invention also relates to devices and methods for minimizingcross-contamination in such apparatus and methods.

BACKGROUND

In recent years, microtitration wells have assumed an important role inmany biological and biochemical applications, such as samplepreparation, genome sequencing, and drug discovery programs. A varietyof multi-well arrangements, constructed according to standardizedformats, are now popular.

There is a need for a multi-well microfiltration apparatus and methodthat provides for the separate collection of filtrate from each well ofan array of wells and addresses problems associated withcross-contamination caused by aerosol formation and/or pendent drops.

The present invention addresses this need and provides a multi-wellmicrofiltration apparatus and method that minimizes or avoidscross-contamination during processing a plurality of liquid samplessimultaneously.

SUMMARY

Various embodiments of the present invention provide a microfiltrationapparatus with a manual touching-off device for processing a pluralityof liquid samples in a multi-well array while reducing or avoidingcross-contamination between the multiple wells. Various embodiments ofthe present invention provide a method for processing a plurality ofliquid samples simultaneously with a multi-well microfiltrationapparatus, wherein the method minimizes or avoids cross-contaminationbetween the multiple wells.

According to various embodiments of the present invention, an apparatusis provided for avoiding cross-contamination due to pendent drops offluid hanging from a plurality of discharge conduits corresponding tothe wells. The plurality of discharge conduits can be disposed, forexample, in a discharged-conduit array, and can be positioned above acorresponding receiving array of receiving wells or receiving holes. Theapparatus can include a carriage configured to carry one of the arraysrelative to the other. For example, the carriage can carry thedischarge-conduit array. The carriage is adapted for movement along apath. The path can be, for example, a first, generally horizontal, axis.The carriage can be adapted for movement from a neutral position whereatthe discharge-conduit array and the corresponding receiving array aresubstantially axially aligned. The apparatus can also include a verticalpositioning assembly supporting one of the arrays, for example, thedischarge-conduit array for movement of the array along a second path,for example, a generally vertical axis. The second path can include, forexample, an elevated position, a lowered position, and an intermediatetouch-off position.

According to various embodiments of the present invention,cross-contamination caused by pendent drops is avoided or minimized byfirst positioning the discharge-conduit array at the touch-off position.At the touch-off position, pendent drops of sample hanging from thedischarge conduits of the discharge-conduit array come into contact withrespective inner sidewalls of respective receiving wells or receivingholes of a corresponding receiving array. The contact between thependent drops and the inner sidewalls can be achieved, for example, byreciprocal movement of one of the discharge-conduit array and thereceiving array along a generally horizontal axis, for example, a first,generally horizontal, linear axis.

According to various embodiments of the present invention, amanually-operated handle is connected to the carriage, directly orindirectly, and to the vertical positioning assembly, directly orindirectly. Movement of the manually-operated handle can, according tovarious embodiments of the present invention, translate into themovement of the vertical positioning assembly along the generallyvertical axis.

According to various embodiments of the present invention a system isprovided wherein an apparatus of the present invention is included in anassembly for enabling movement of the apparatus from a first treatmentstation to a second treatment station. The assembly can include a commonplatform on which the first and second treatment stations can besupported, as by, for example, fixing, securing, mounting, orconnecting.

According to various embodiments of the present invention, a method ofavoiding or minimizing cross-contamination due to pendent-drops isprovided whereby a touch-off procedure is conducted to enable pendentdrops hanging from discharge conduits of an array to contact the innersidewalls of respective receiving wells or receiving holes of acorresponding receiving array. The contact can occur in a manner tocarry-away, such as by wicking, or hydrophilic action, the pendent dropshanging from the distal ends of discharge conduits. According to variousembodiments of the present invention, the contact between the drops andthe inner sidewalls can occur without contact between the dischargeconduits themselves and the inner sidewalls, or with contact betweenonly distal tips of the discharge conduits and the respective innersidewalls. Multi-step methods are also provided according to variousembodiments of the present invention whereby one or more touch-offprocedures are carried out at two or more sample treatment stations.

According to various embodiments of the present invention, a device isprovided for shifting a discharge-conduit array in two or moredirections from a reference, beginning, or home position along agenerally horizontally extending axis, and then returning the array backto the home position, for example, back and forth one time. The shiftingdevice can include a manually-operated actuator for moving thearray-carrying carriage, for example, without a stepper motor. In suchan embodiment, the shifting can be performed by an operator moving oractuating a handle in a manner to enable control over the speed, timing,frequency, and forcefulness of the manual shifting.

The invention may be more fully understood with reference to theaccompanying drawing figures and the descriptions thereof. Modificationsthat would be recognized by those skilled in the art are considered apart of the present invention and within the scope of the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and manner of operation of the invention, together withthe further objects and advantages thereof, may best be understood byreference to the following description taken in conjunction with theaccompanying drawings, in which identical reference numerals identifyidentical elements in the different figures, and in which:

FIG. 1 is a perspective view of a multi-well microfiltration device thatcan be used with the apparatus and method of an embodiment of thepresent invention;

FIG. 2 is an exploded view of the multi-well microfiltration device ofFIG. 1;

FIG. 3 is a partial cross-sectional side view of the multi-wellmicrofiltration device of FIGS. 1 and 2;

FIG. 4 shows, in enlarged detail, a microfiltration well with adischarge conduit taken from a sectional view of FIG. 3;

FIG. 5 is a partial cross-sectional side view showing a microfiltrationwell with discharge conduit and an aerosol guard useful in the apparatusand method of an embodiment of the present invention;

FIG. 6 is an exploded view of a microfiltration well of adischarge-conduit array showing a membrane-support structure in the formof three fin-like support buttresses;

FIG. 7 is an end view from one end of a carriage assembly for effectingrelative movement between the discharge conduits of a discharge-conduitarray and the receiving wells or receiving holes of a receiving array,useful with the apparatus and method of an embodiment of the presentinvention;

FIG. 8 is a partially exploded, perspective view showing a carriageassembly for effecting relative movement between a discharge-conduitarray and a receiving array, according to an embodiment of the presentinvention;

FIGS. 9(A)-9(C) are cross-sectional side views showing a touch-offoperation according to an embodiment of the present invention whereby aplurality of discharge conduits from a discharge-conduit array islaterally shifted to the right and to the left to cause contact betweenpendent drops hanging from the discharge conduits and inner sidewalls ofthe respective receiving wells;

FIG. 10(A) is a partially schematic top plan view showing aspring-loaded touch-off mechanism in its normal, or neutral, position;

FIG. 10(B) is a partially schematic top plan view showing thespring-loaded touch-off mechanism of FIG. 10(A) in a first, shiftedposition;

FIG. 10(C) is a partially schematic top plan view showing thespring-loaded touch-off mechanism of FIGS. 10(A) and 10(B) in a second,shifted position;

FIG. 11 is a cross-sectional side view in partial breakaway of amanually-operated device according to an embodiment of the presentinvention with the vertical positioning system and carriage in theelevated position and the handle in the beginning position;

FIG. 12 is a cross-sectional side view in partial breakaway of a deviceaccording to an embodiment of the present invention with the carriageand discharge-conduit array in the touch-off position;

FIG. 13 is a cross-sectional side view in partial breakaway of a deviceaccording to an embodiment of the present invention with the carriageand discharge-conduit array in the lowered position and the handle inthe set position;

FIG. 14 is an enlarged cross-sectional view of a device according to anembodiment of the present invention showing a carriage anddischarge-conduit array in a touch-off position relative to acorresponding receiving array of deep receiving wells;

FIG. 15 is an enlarged cross-sectional view of a device according to anembodiment of the present invention showing a carriage anddischarge-conduit array in a touch-off position relative to acorresponding receiving array of shallow receiving wells or microwells;

FIG. 16 is a cross-sectional front view of a device according to anembodiment of the present invention with the carriage and a deep-welldischarge-conduit array in the lowered position and the handle in theset position;

FIG. 17 is a cross-sectional front view of a device according to anembodiment of the present invention with the carriage and a shallow-welldischarge-conduit array in the touch-off position;

FIG. 18 is a partial cross-sectional view of a device according to anembodiment of the present invention showing the carriage anddischarge-conduit array in the touch-off position and the handle in theelevated position.

FIG. 19 is a partial cross-sectional view of a device according to anembodiment of the present invention showing the carriage anddischarge-conduit array in the elevated, release, or beginning positionand the handle in the beginning and release positions;

FIG. 20 is a partial cross-sectional view of a device according to anembodiment of the present invention showing the carriage anddischarge-conduit array in a lowered position and the handle in a setposition;

FIG. 21 is a perspective view of a device according to an embodiment ofthe present invention showing the carriage and discharge-conduit arrayat a first treatment station in the touch-off position;

FIG. 22 is a perspective view of a device according to an embodiment ofthe present invention showing the carriage and discharge-conduit arrayin the elevated or open position and the handle in the beginning orrelease position;

FIG. 23 is a perspective view of a device according to an embodiment ofthe present invention showing the carriage and discharge-conduit arrayin the lowered or sealed position and the handle in the set position;

FIG. 24 a is a partial cross-sectional view of a device according to anembodiment of the present invention showing the carriage and dischargeconduit array in the touch-off position and the handle in the elevatedposition;

FIG. 24 b is a partial cross-sectional view, of the reverse side of thedevice shown in FIG. 24 a;

FIG. 25 is a partial cross-sectional view of a device according to anembodiment of the present invention showing the carriage anddischarge-conduit array in the elevated, beginning, or release positionand the handle in the beginning or release position;

FIG. 26 is a partial cross-sectional view of a device according to anembodiment of the present invention showing the carriage anddischarge-conduit array in the lowered, sealed, or closed position andthe handle in the set or lowered position; and

FIG. 27 is a partial side view of a device according to an embodiment ofthe present invention showing the handle in the elevated position andthe carriage in the touch-off position.

Other various embodiments of the present invention will be apparent tothose skilled in the art from consideration of the specification andpractice of the invention described herein, and the detailed descriptionthat follows. It is intended that the specification and examples beconsidered as exemplary only, and that the true scope and spirit of theinvention includes those other various embodiments.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE PRESENT INVENTION

Although it is to be recognized that either the discharge-conduit arrayor the receiving array can be vertically moved, horizontally moved, ormoved along both a horizontal plane and a vertical axis, the presentinvention is described in detail with respect to movement of an upperdischarge-conduit array. According to various embodiments of the presentinvention, a manually-operated apparatus is provided for avoidingcross-contamination due to pendent drops of fluid hanging from aplurality of discharge conduits disposed in a discharge-conduit arrayabove a corresponding receiving array of receiving wells or receivingholes. According to various embodiments of the present invention, theapparatus includes a carriage configured to move the discharge-conduitarray horizontally in two or more directions. The carriage can beconfigured to carry the discharge-conduit array linearly in a reciprocalmovement in either of at least two directions along a generallyhorizontal axis. The carriage can carry the array from, for example, aneutral position to a touch-off position. According to variousembodiments of the present invention, the carriage can carry thedischarge-conduit array horizontally, for example, reciprocallyhorizontally, to first and second, different, touch-off positions.According to various embodiments of the present invention, the carriagecan be configured to carry the discharge-conduit array in a plurality ofdifferent substantially horizontal directions into a plurality ofdifferent positions.

The shifting of the discharge-conduit array in various directions, forexample, in various horizontal directions, can effect a touch-offoperation whereby pendent drops of fluid hanging from the dischargeconduits of the array are brought into contact with the inner sidewallsof respective receiving wells or receiving holes of a correspondingreceiving array. The shifting operation can provide a mechanism wherebythe hydrophilicity, or wicking, of the pendent drops of fluid enablesthe drops to be gently carried away from the discharge conduits withoutrequiring a shaking action and without necessitating a contact of thedischarge conduit itself with any portions of the sidewalls of thereceiving wells or receiving holes. According to various embodiments ofthe present invention only the distal tips of the discharge conduitscontact the inner sidewalls of the respective corresponding receivingwells or receiving holes.

The discharge conduit can be shifted from being axially aligned with thereceiving wells or receiving holes to positions having parallel, butnon-axial, orientations with respect to the corresponding receivingwells or receiving holes.

According to various embodiments of the present invention, a verticalpositioning assembly is provided for supporting the discharge-conduitarray for linear movement along a second, generally vertical, axis. Thevertical positioning assembly can provide movement of thedischarge-conduit array between, for example, an elevated position, alowered position, and an intermediate position. The elevated positioncan be a position, for example, an open position whereat the dischargeconduits clear the receiving wells or receiving holes of the receivingarray. The lowered position can be a position, for example, a sealedposition whereat the discharge conduits extend down into respectivereceiving wells or receiving holes of a corresponding receiving array.The intermediate position can be, for example, a touch-off position inbetween or intermediate to the lowered and elevated positions. Thetouch-off position can be a position whereat pendent drops hanging fromthe discharge conduits contact respective sidewalls of respectivereceiving wells or receiving holes of the receiving array. According tovarious embodiments of the present invention, methods are providedwhereby movement of the discharge-conduit array while the array isvertically-positioned for touch-off results in a shifting of thedischarge-conduit array from a neutral position to one or more touch-offpositions. The movement of the discharge conduit array can be, forexample, a linear reciprocal movement.

According to various embodiments of the present invention, amanually-operable handle can be connected to the carriage directly, orindirectly. According to various embodiments of the present invention,the manually-operable handle can be connected to the verticalpositioning assembly, either directly or indirectly. The handle can beconfigured with respect to the carriage, with respect to the verticalpositioning assembly, or with respect to both the carriage and thevertical positioning assembly, such that movement of the handletranslates into the reciprocal movement of the carriage, the linearmovement of the vertical positioning assembly, or both.

The handle can be configured for pivotal movement, for example, an upand down reciprocal movement, a back and forth reciprocal movement, anarcing movement, or the like, for example, from a beginning or elevatedposition to a set position. The handle can be configured for movementfrom a set, locked, or lowered position to an elevated and/orintermediate position, and if an intermediate or touch-off position isused, from there to a release or elevated position. The handle caninclude two interworking levers that together or separately move toachieve the beginning position of the handle, the set position of thehandle, the touch-off or intermediate position of the handle, and therelease or open position of the handle. The touch-off position can bethe same as the elevated position.

According to various embodiments of the present invention, the beginningposition of the handle can be an elevated position, the set position ofthe handle can be a depressed position, and if a separate touch-offposition of the handle is used, it can be intermediate to, or inbetween, the beginning position and the set position. The releaseposition can be the same position as the beginning position. In therelease position, for example, the carriage can be configured formovement from a first treatment station to one or more additionalstations, such as a second treatment station, whereby the first andsecond treatment stations in such an embodiment can be, for example,supported by a common platform as by mounting, fixing, securing, and/orconnecting.

According to various embodiments of the present invention, a vacuumsystem can be provided in a system that includes an apparatus of thepresent invention. The vacuum system can provide a device for drawing avacuum through the discharge-conduit array, an array of receiving holes,both arrays, and the like. The vacuum system can be configured tooperate only when the carriage and discharge conduit array are in thelowered position.

According to various embodiments of the present invention, an apparatusis provided whereby the carriage is connected to the handle such thatwhen the handle is in the elevated beginning position, the verticalpositioning assembly positions the carriage and, if present, adischarge-conduit array, in the elevated position. The carriage can beconnected to the handle such that when the handle is in the setposition, the vertical positioning assembly positions the carriage and,if present, a discharge-conduit array, in the lowered position. Thecarriage can be connected to the handle such that when the handle is inthe intermediate position, the vertical positioning assembly positionsthe carriage and, if present, a discharge-conduit array, in thetouch-off position.

According to various embodiments of the present invention, when thehandle is depressed into the set position, a releasable lock isactivated that maintains the vertical positioning assembly in the setposition. The lock maintains the set position until it is released, forexample, by a manual operation such as by pressing a button. Accordingto various embodiments of the present invention, the handle includes twolevers and both levers are depressed to achieve the set position and toactivate the releasable lock.

According to various embodiments of the present invention, the receivingarray is positioned on or in a platform. The receiving array can be, forexample, secured into place, as by being held, maintained, fixed,mounted, or in any way restricted in movement, by the platform. Systemsaccording to various embodiments of the present invention are providedwhereby such a platform further includes a second treatment station forsecuring a second receiving array of receiving wells or receiving holes.According to such embodiments, the platform can be configured so as toprovide a position-shifting assembly for moving the carriage from thefirst treatment station to the second treatment station. Theposition-shifting assembly can include rails, tracks, guides, bumpers,or any combination of features that directs the carriage from the firsttreatment station to the second treatment station whereby thedischarge-conduit array can be axially aligned with two differentreceiving arrays at different treatment stations.

According to various embodiments of the present invention, shifting ormovement between the first treatment station and the second treatmentstation can be enabled, for example, when the vertical positioningassembly supports the discharge-conduit array in the elevated position,for example, when the handle is in the beginning position. Similar, orthe same, movements of the handle at the second treatment station, as atthe first treatment station, can result in a second discharge operationwhereby samples from the discharge-conduit array are forced into orthrough the receiving wells or receiving holes of a respective secondreceiving array at the second treatment station.

According to various embodiments of the present invention, the firsttreatment station can be, for example, a sample wash station or a samplebinding station. The second treatment station can be a sample collectionstation or a second sample wash station. Multiple operations such aswashes can be carried out at the first treatment station, the secondtreatment station, or at both the first treatment station and the secondtreatment station.

According to various embodiments of the present invention, a method isprovided for avoiding cross-contamination due to pendent drops of fluidhanging from a plurality of discharge conduits disposed in adischarge-conduit array above a corresponding receiving array ofreceiving wells or receiving holes. The methods of various embodimentsof the present invention can include providing a carriage-positioningassembly that can effect movement of the carriage from a first treatmentstation to a second treatment station, for example, between twotreatment stations on a common platform. The touch-off operationaccording to various embodiments of the present invention can beeffected at the first treatment station, at the second treatmentstation, or at both the first treatment station and the second treatmentstation.

According to various embodiment of the present invention, a shiftingmeans is provided for effecting the movement of the carriagehorizontally along the first axis. The shifting means can include anactuator for manually moving the receiving array relative to thedischarge-conduit array.

Thus, in an embodiment of a device according to the present invention,an actuator is provided that is in mechanical communication with thedischarge conduit array such that manual force applied to the actuatorinduces horizontal, for example, linear movement of at least one of thedischarge-conduit array and the receiving array.

The present invention also provides methods for reducing or avoidingcross-contamination, removing inhibitory wash solutions, and increasingthe percent yield of the archiving, collection, and filtrationoperations of a microfiltration apparatus according to the presentinvention, by using the manual touch-off apparatus and methods taughtherein.

Another aspect of the present invention provides a method for separatelycollecting filtrate from an array of microfiltration discharge-conduitwells in a corresponding array of closed-bottom receiving wells held bya receiving tray situated below the microfiltration discharge-conduitwell array.

In an embodiment of the present invention, a method is provided thatincludes the steps of:

(A) placing one or more fluid samples in a plurality of microfiltrationwells discharge conduits of a discharge-conduit array;

(B) drawing a vacuum along pathways extending from each dischargeconduit downward through a plane defined by an upper surface of thereceiving tray at a point at or adjacent a corresponding receiving wellto a region beneath the receiving array, thereby causing a filtrate toflow from each discharge conduit and to collect or pass through therespective wells or receiving holes of the receiving array; and

(C) obstructing aerosols formed from the filtrate at any one dischargeconduit from moving across the upper surface of the receiving array to anon-corresponding receiving well or receiving hole of the receivingarray, thereby limiting cross-contamination.

According to an embodiment of the present invention, each vacuum pathwaypasses through a gas-permeable matrix disposed in a cavity between thedischarge-conduit array and the receiving array. The gas-permeablematrix can be comprised of a porous hydrophilic polymer material, suchas ethyl vinyl acetate (EVA) or the like. In an exemplary arrangement,the gas-permeable matrix circumscribes the region between each dischargeconduit and a corresponding receiving well or receiving hole.

According to yet another embodiment of the present invention, the vacuumpathways pass through the plane of the receiving array upper surface byway of vents that traverse the receiving array proximate each of thereceiving wells or receiving holes of the receiving array. Thegas-permeable matrix can also cover the vents.

In yet other various embodiments of the present invention, each of thevacuum pathways extends from one or more respective microfiltration welldischarge conduit into a respective receiving well or receiving holeprior to passing through the vents.

According to various embodiments of the present invention, a receivingarray is used that has receiving holes, for example, open-bottom wells,wherein the vacuum pathways pass through the plane of the receivingarray upper surface and then down and out of the open bottoms of thewells.

The receiving wells or receiving holes can include, according to variousembodiments of the present invention, a first plate having a pluralityof columns and a second plate having a plurality of discharge conduits.Each column of the first plate can have a first inner bore defining alumen within the column, and an end region for receiving a filter mediumwithin the column. The end region can define a second inner bore havinga diameter greater than that of the first inner bore, and a transitionregion that joins the second inner bore to the first inner bore. Afilter medium for filtering sample can be positioned within each columnend region, adjacent the transition region. Each discharge conduit canhave an upstanding upper end region aligned with and received within acorresponding column end region so as to form a substantiallyfluid-tight interface therebetween. The discharge conduit upper endregion has a terminal rim region for supporting a circumferential regionof the filter medium such that each filter medium is held between acolumn transition region and the terminal rim region of a correspondingdischarge conduit.

After the fluid sample is filtered through the filter and passed intothe sample well as described, pendent drops of liquid sample can remainfixed to the surface of the distal tips of the discharge conduits, thatis, to the “drip directors” openings. It is desirable to remove suchpendent drops from the tips of the drip directors so that they leave thetips and are received by the receiving well or receiving hole. Theoperation according to various embodiments of the present invention, foreffecting such a transfer is referred to herein as a “touch-off” of or“touching-off” the pendent drops.

In a touching-off method according to various embodiments of the presentinvention, the discharge-conduit array is moved in opposite horizontaldirections to touch opposite surfaces of the same respectivecorresponding receiving well or receiving hole. The provision of thesample well chamfered surface promotes more thorough touching-off of thependent drops with minimum or no contact required between the dischargeconduits and the inner sidewalls. Because the receiving well chamfer isangled to match the angle of the discharge conduit chamfer, the pendentdrops hanging from the drip directors are provoked to be pulled towardinner sidewalls of the receiving wells. The touching-off operation canbe useful in minimizing or avoiding cross contamination caused bydripping of liquid sample into a non-aligned receiving well duringremoval of the receiving array.

In further embodiments of the present invention, a vacuum system isprovided for drawing adherent drops of fluid hanging from the dischargeconduits in a direction away from the receiving wells and up into thedischarge conduits.

According to yet further various embodiments of the present invention, amethod is provided that includes:

(i) touching-off, in a substantially simultaneous fashion, pendent dropsof fluid hanging from discharge conduits of a discharge-conduit array toinner sidewalls of respective receiving wells or receiving holes of acorresponding receiving array; and

(ii) drawing adherent drops of fluid hanging from the discharge conduitsin a direction away from the respective receiving wells or receivingholes of the corresponding receiving array, and up into the dischargeconduits.

According to various embodiments of the present invention, a vacuumchamber is provided that communicates with the discharge-conduit arrayfrom a side thereof opposite the receiving array. Evacuation of thevacuum chamber is effective to urge pendent drops of fluid hanging fromthe discharge conduits in a direction away from the receiving wells orreceiving holes of the receiving array and into the discharge conduits.

According to various embodiments of the present invention, an apparatusis provided that can include:

(i) a carriage configured to carry a discharge conduit array having aplurality of discharge conduits with distal ends, the carriage beingadapted for linear reciprocal movement in either of two directions alonga first, generally horizontal, axis from and to a neutral positionwhereat the discharge-conduit array and the receiving array aresubstantially axially aligned;

(ii) an actuator or handle for manually moving the carriage and thus thedischarge-conduit array and the receiving array relative to each other agiven distance from the neutral position in one of the two directionsdepending upon the direction of manual force applied to the carriagesuch that pendent drops of fluid hanging from the distal ends of thedischarge conduits are simultaneously touched-off to inner sidewalls ofrespective receiving wells or receiving holes of the correspondingreceiving array, and, optionally,

(ii) a compression spring connected to the actuator or handle in amanner permitting the spring (a) to provide a predetermined amount ofresistance to movement of the actuator or handle from the neutralposition, and (b) to compensate for or absorb some of any linearovershoot due to excess manual effort beyond the amount required tomanually move or shift the carriage and discharge conduits.

According to various embodiments of the present invention, the actuatorcontains at least a lever, wherein the lever can rotate about an axis ofrotation. According to various embodiments of the present invention, thelever can pivot about a pivot point. According to various embodiments ofthe present invention, a pivot point can be provided mounted on orconnected to a device, and the device can further include a receivingarray, and may further include a recess or opening for holding thereceiving array. The actuator can further include or be made of ahandle, for example, a two-part handle having two lever arms.

According to various embodiments of the present invention, the carriageis configured to carry the discharge-conduit array, while the receivingarray remains stationary. A vertical positioning assembly can bedisposed on or in conjunction with the carriage to support thedischarge-conduit array for movement such as linear movement along asecond, generally vertical, axis between a lowered position whereat thedischarge conduits extend down into respective receiving wells orreceiving holes, and an elevated position whereat the discharge conduitsclear the receiving wells.

According to various embodiments of the present invention, the carriageis configured to carry the receiving array while the discharge conduitarray remains stationary. A vertical positioning assembly can bedisposed on or in conjunction with the carriage to support the receivingarray for movement such as linear movement along a second, generallyvertical, axis between an elevated position whereat the dischargeconduits extend down into respective receiving wells or receiving holes,and a lowered position whereat the discharge conduits clear thereceiving wells or receiving holes.

According to various embodiments of the present invention, a horizontalcarriage and vertical positioning assembly system is provided thatenables horizontal movement of a first array in a first direction andhorizontal movement of a second array in a second direction that differsfrom the first direction. The first array can be a discharge-conduitarray and the second array can be a receiving array, or vice versa.

Still a further embodiment of the present invention provides a methodfor avoiding cross-contamination due to pendent drops of fluid hangingfrom a plurality of discharge conduits disposed in an array above acorresponding array of closed-bottom receiving wells or receiving holes.According to various embodiments of the present invention, the methodincludes:

(i) touching-off, in a substantially simultaneous fashion, pendent dropsof fluid hanging from the discharge conduits to inner sidewalls ofrespective receiving wells; and

(ii) drawing pendent drops of fluid hanging from the discharge conduitsin a direction away from the corresponding receiving array and into thedischarge conduits.

The touching-off step can be carried out by shifting thedischarge-conduit array or the receiving array, along a plane that issubstantially orthogonal to the longitudinal axes of the receivingwells, while the receiving wells are maintained in a substantially fixedposition. Each of the discharge conduits can be shifted into contactwith inner sidewall portions of respective receiving wells, and can thenbe shifted into contact with laterally opposing inner sidewall portionsof the same respective receiving wells.

Another embodiment of the present invention provides an actuator formanually moving at least one of the discharge-conduit array and thereceiving array relative to the other. The actuator can include a handleand/or lever in mechanical communication with the discharge-conduitarray, for example, through a carriage, such that manual force appliedto the handle or a part thereof, results in movement of thedischarge-conduit array in a generally horizontal direction. In thisway, the application of a manual force to the handle causes thedischarge-conduit array to shift. The distal ends of the dischargeconduits can be shifted so that hanging pendent drops make contact withsidewall portions of respective receiving wells or receiving holes ofthe receiving array. Then, by the application of a different manualforce to the actuator, the discharge-conduit array can be shifted sothat the hanging drops of fluid contact laterally opposing sidewallportions of the respective receiving wells or receiving holes. Thetouching-off can be achieved according to the present invention when thedischarge-conduit array is in, for example, an archiving, collection, orfiltration position such as shown as station “a” in FIG. 11, or in, forexample, a wash or waste collection position such as shown as station“b” in FIG. 11.

The step of drawing pendent drops of fluid can be affected byestablishing a reduced pressure such as by a vacuum, above the dischargeconduits.

Further various embodiments of the present invention are described andillustrated herein, and will become obvious with reference to thefollowing more detailed description of those various embodiments. Theembodiments of the present invention described herein are only exemplaryillustrations thereof. The following detailed description of variousembodiments of the present invention is also exemplary in nature.

FIGS. 1-3 show, in perspective, exploded and partial side-sectionalviews, respectively, an embodiment of a multi-well microfiltrationapparatus constructed in accordance with various embodiments of thepresent invention. Even greater details about the multi-wellmicrofiltration apparatus and systems that use the apparatus, can befound in U.S. Pat. No. 6,159,368, which is incorporated herein in itsentirety by reference.

In the assembly stage of manufacture, a filter sheet or membrane,indicated in FIG. 2 by the reference numeral 8, is located between acolumn tray, or plate, 10 having an array of open-bottom mini-columns,such as 12, and a drip-director tray, or plate, 14 having an array ofdrip directors, such as 16, corresponding to the mini-columns. Uponregistering and mating mini-columns 12 with drip directors 16, adischarge-conduit array is formed in the form of a multi-wellmicrofiltration array, denoted generally in FIG. 3 by the referencenumeral 18, each mini-column having a discrete filter element or medium(e.g., a plug, disc, or the like), such as 8 a and 8 b, positionedtherein. The inner walls of each mated mini-column/drip-director pairbound a flow pathway that extends downward through the well 18.

As shown in FIGS. 2 and 3, each microfiltration well has an interiorregion, or lumen, that is substantially circular in horizontalcross-section. It should be appreciated, however, that microfiltrationwells of any desired geometrical cross-section (e.g., oval, square,rectangular, triangular, etc.) could be used. Similarly, the wells maybe of any desired shape when viewed along their longitudinal axes, e.g.,straight, tapered or other shape. In one embodiment, the walls of eachwell have a slight outward taper (i.e., the well diameter increases)along the direction extending from the well's upper, loading end towardthe filter medium.

Greater details about the plates, filters, columns, drip directors, andother components of the illustrated embodiment, and methods of makingthose components, can be found in U.S. Pat. No. 6,159,368, which isincorporated herein in its entirety by reference.

With reference once again to FIGS. 1-3, an upper vacuum chamber 20 issituated above column plate 10. Upper vacuum chamber 20 is adapted formovement between (i) a mounted position, whereat four dependingcircumferential walls, denoted as 20 a, form a substantially airtightseal with an upper, peripheral surface of column plate 10 via aninterposed resilient gasket 21, and (ii) a retracted position, whereatchamber 20 is spaced apart from column plate 10. The hollow interior ofchamber 20 is pneumatically connectable to an external vacuum source viaa hosecock 23 extending through the top of chamber 20. A reducedpressure can be established above the sample wells by bringing chamber20 to its mounted position atop column plate 10 and then evacuatingchamber 20.

In some situations, it may be desirable to establish an increasedpressure above the sample wells (e.g., to facilitate the flow of samplesthrough the filter media and out of the wells via the lower dischargeconduits). In such cases, chamber 20 can be pressurized by way of asuitable pressure source (e.g., a pump).

A receiving array in the form of a receiving plate or receiving plate 24is located below drip director plate 14. Receiving plate 24 includes anupper planar surface, denoted as 25, and an array of closed-bottomwells, such as 26, depending therefrom. The receiving-well arraycorresponds to the drip-director array, permitting the separatecollection of filtrate from each sample well. The receiving plate isadapted to fit inside an open reservoir of a lower vacuum chamber,denoted as 29, with the receiving wells or receiving holes extendingdown into the reservoir.

Apertures or vents, such as 28, extend through the upper planar surface25 of receiving plate 24. For reasons that will become apparent, atleast one aperture should be located adjacent each receiving well. Theapertures 28 permit fluid communication between the regions above andbelow the plate 24. By this construction, a vacuum drawn from beneaththe receiving plate will extend to the regions above the plate andinside the wells.

Although not shown in the figures, the present invention also provides aplate like receiving plate 24, except having open-bottom wells asopposed to the closed-bottom wells of plate 24. Otherwise, the plate ofopen-bottom wells is configured like receiving plate 24. That is, theplate of open-bottom wells provides structure for effectively carryingout filtrations and/or washings, while avoiding cross-contamination.However, instead of separately collecting filtrate in the various wells,the filtrate passes through the wells and out of the open bottoms. It iscontemplated that the plate of open-bottom wells will be used in amanner like that described herein for plate 24, except that thesituation will not call for the separate collection of filtrate. Forexample, the plate of open-bottom wells is particularly useful inperforming intermediate washings. As used herein, “collection plate” and“receiving plate” are used synonymously and interchangeably, with eitherterm referring to a plate, intended for placement beneath adrip-director array, having either open-bottom wells or closed-bottomwells, as appropriate for the task at hand. Where the separatecollection of filtrate is to take place, it is understood that the wellsare of a closed-bottom type. Optionally, a receiving plate havingopen-bottom wells may be formed without vent features (such as 28), asthe vacuum can flow directly down and out through the bottom of eachwell.

A cross-flow restrictor (also referred to as an aerosol guard), denotedas 30, which is generally pervious to gases but substantially imperviousto aerosols, is interposed between the upper surface of receiving plate24 and the lower surface of drip-director plate 14. In the illustratedembodiment, cross-flow restrictor 30 has a plurality of passages, suchas 32, arranged in an array complementing the receiving-well array anddrip-director array. Passages 32 permit filtrate to pass from each dripdirector 16 to a corresponding receiving well 26. In the illustratedarrangement, each drip director 16 extends through a respective passage.Except for such passages, cross-flow restrictor 30 substantially fillsthe area between the confronting faces of the drip-director andreceiving-well plates (14, 24).

Preferably, means are provided for supporting the assembled mini-columnand drip-director plate arrangement, and assisting in the formation ofan airtight seal between this arrangement and the lower vacuum chamber29. In the illustrated embodiment, a rectangular carriage frame, denotedas 38, is configured to support the mini-column and drip-director plateassembly. Clamps 34, 36 are pivotally mounted about generally verticallyextending axes at opposing ends of frame 38. Clamps 34, 36 are operableto engage and hold the column and drip-director assembly on frame 38,with a lower peripheral edge 40 of the column and drip-director plateassembly pressed against a gasket 42 disposed on the upper surface offrame 38 about the frame's central opening.

A spring-loaded centering pin, such as 37 and 39, may extend througheach clamp 34, 36. In the embodiment of FIG. 3, centering pin 37 has ashank that is urged by a spring 41 to sit within a complementary recessor depression 43 formed in a sidewall of column plate 10. In anotherembodiment (not shown), three spring-loaded centering pins are employed,with two pins located at positions on a long side of the arrangement andone pin located at a position on a short side, together operable to pushthe tray against a corner. In this way, the components can be readilycentered (on axis).

A stepped gasket, indicated generally at 44, is disposed adjacent alower surface of frame 38 about the frame's central opening. Gasket 44has (i) an upper, inwardly projecting flap portion, denoted as 44 a,having a lower surface adapted to engage an upwardly projecting ridge 48disposed about the periphery of receiving plate 24, and (ii) a lowerflap portion, denoted as 44 b, that extends diagonally downward andoutward for engaging an upper surface 50 surrounding the open reservoirof lower vacuum chamber 29. A central plateau region of stepped gasket44, denoted as 44 c, is secured to frame 38 by any suitable means. Forexample, central plateau region 44 c can be attached using an adhesiveand/or fasteners. In one embodiment, gasket 44 is interposed betweenframe 38 and a rectangular clamping frame (not shown). In thisembodiment, the rectangular clamping frame is disposed adjacent theplateau region 44 c of gasket 44, on a side of gasket 44 opposite frame38. The clamping frame is then snugly secured to frame 38 using threadedfasteners that pass through aligned passages (not shown) formed in theclamping frame and gasket, and are received in internally threaded boresextending partially into frame 38 from the frame's lower surface.Together, upper gasket 42 and lower gasket 44 assist in formingsubstantially airtight seals between (i) the upper microfiltration wellassembly and the carriage frame, and (ii) the carriage frame and thelower vacuum chamber assembly, respectively.

The gaskets (21, 42, and 44) may be formed of any deformable, resilient,substantially inert material capable of forming a seal. Examples of suchmaterials are silicone, rubber, polyurethane elastomer and polyvinylchloride. The thickness of each gasket is not critical, provided onlythat it is sufficient to form a seal. Typical gasket thicknesses willrange from about 1 mm to about 5 mm.

Once appropriate airtight seals are formed, evacuation of lower vacuumchamber 29 establishes a substantially uniform pressure drop over all ofthe sample wells 18, permitting a plurality of individual samples (e.g.,up to ninety-six in the illustrated embodiment) to be processedsimultaneously on the membrane of choice.

Those skilled in the art will recognize that the choice of filter mediumwill depend on the intended use of the well. Exemplary filter materialsthat can be used can be found, for example, in U.S. Pat. No. 6,159,368,which is incorporated herein in its entirety by reference.

In another embodiment the filter medium is a porous element that acts asa frit, serving to contain a column packing material (e.g.,reversed-phase or size-exclusion packings).

Various aspects of the present invention address problems pertaining to(i) cross-contamination due to wicking across a common filter sheet and(ii) individual filter elements entrapping sample constituents withinsubstantial dead volumes, and are discussed more fully in U.S. Pat. No.6,159,368, which is incorporated herein in its entirety by reference.

In the embodiment of FIG. 4, mini-column 12 is formed with a bore 12 aand a counterbore 12 b, the latter extending upwardly from themini-column's lower end or lip 12 c. Between the bore 12 a andcounterbore 12 b, lies a transition region. The transition regionprovides a constricted-diameter region, or shoulder, within themini-column lumen capable of cooperating with an upper portion of acorresponding drip director to maintain the filter element in place. Thejunctions of the transition region with the bore and counterbore may beof any suitable shape, for example, as described in U.S. Pat. No.6,159,368, which is incorporated herein in its entirety by reference.

According to the embodiment depicted in FIG. 4, the transition regionbetween bore 12 a and counterbore 12 b defines an internal, annularshoulder, denoted as 12 d. In this embodiment, each of the junctions ofshoulder 12 d with bore 12 a and counterbore 12 b defines a hard angleor corner. Between such junctions, the shoulder 12 d takes the form ofan annular wall having a substantially constant taper, with a decreasingcircumference along the direction from counterbore 12 b to bore 12 a.Longitudinally, the surface of shoulder 12 d is oblique to the surfacesof bore 12 a and counterbore 12 b. Preferably, the surface of shoulder12 d forms an acute angle with a plane perpendicular to themini-column's central axis and extending through the junction ofshoulder 12 d with counterbore 12 b. In one embodiment, this angle,denoted as α in FIG. 4, falls within the range of about 30-85 degrees;and is preferably within the range of about 60-85 degrees.

Drip-director 16 is configured to facilitate elution of a mobile phasefrom the well by funneling it toward a lower opening. In the embodimentof FIG. 4, drip director 16 includes (i) an annular edge or rim 16 adisposed above the plane of the upper surface of drip-director plate 14,(ii) depending convergent sidewalls 16 b, and (iii) a downspout oroutlet port 16 c disposed below the plane of the lower surface ofdrip-director plate 14. The downwardly sloping, inner surface of theconvergent sidewalls 16 b, between rim 16 a and outlet port 16 c,defines a conical and/or horn-shaped cavity at the lower region of thewell lumen.

As previously mentioned, an upper portion of drip director 16 providessupporting structure adapted to abut a lower peripheral edge region ofthe filter element. In the embodiment of FIG. 4, such structure takesthe form of upper, annular rim 16 a. The surface area of the uppermostregion of rim 16 a (i.e., the portion of rim 16 a that directlyconfronts, and is available to support, the lower peripheral edge regionof the filter element) may vary. In one preferred embodiment, theuppermost region of rim 16 a defines a narrow circular line. In thisembodiment, the contact between rim 16 a and filter element 8 a istangential in nature. That is, the region of contact between rim 16 aand filter element 8 a defines a very thin, circular line. Rim 16 acontacts no more than about 15%, and preferably less than about 10%, andmore preferably less than about 5% of the bottom surface area of thefilter element 8 a.

In the illustrated embodiment, the peripheral edge region of filterelement 8 a is preferably pinched or compressed between shoulder 12 dand rim 16 a in a manner effective to secure the filter element in placeand to press its circumferential side-edge against the inner surface ofthe column lumen. This arrangement discourages upward or downwardmovement of the filter element and prevents leakage around its edges.

FIG. 5 is a partial side-sectional view showing a microfiltration wellconstructed in accordance with one preferred embodiment of theinvention. Filter element 8 a is compressed between drip-director rim 16a and mini-column shoulder 12 d such that the membrane is securely heldin place. Further, the compression fit causes the outer circumferentialside-edge region of the filter element to press against the inner wallof the column lumen in a manner effective to avoid any bypassing offluid around the edges of the filter element. Shoulder 12 d extends intothe mini-column lumen at an angle α of about 45 degrees. Further, theuppermost surface area of rim 16 a is minimal, approaching that of acircular line, so that only the outermost perimeter of the filterelement's lower surface is in contact therewith.

With continued reference to FIG. 5, both the compression and the deadvolume have been estimated for a filter element in one suchmicrofiltration well using the computer-aided engineering package“Pro/ENGINEER” (Release 18), by Parametric Technology Corporation(Waltham, Mass.). The membrane compression for a 950 μm thick QM-B(Whatman, Inc., Tewksbury, Mass.) filter element having a diameter of6.88 mm is estimated to be only about 2.6 μl (area 52 in FIG. 5), andthe dead volume for such a filter element is estimated to be only about3 μl (area 54 in FIG. 5).

Beneath the filter element 8 a, the inner surface of the convergentsidewalls 16 b of drip director 16 define a cavity. The cavity isconfigured to expose the great majority of the filter element's lowersurface to open, or free, space. By providing such free space below thefilter element 8 a (i.e., volume between the drip director's convergentsidewalls 16 b and the lower surface of the filter element),preferential flow pathways are avoided.

In another embodiment, to prevent sagging or dislodgement of the filterelement into the cavity, the invention provides structure for supportingcentral points or regions of each filter element. For example, a supportbuttress may be disposed within the cavity of drip director 16 toprovide a resting point, edge or surface for one or more centrallylocated regions of the filter element's lower surface, as is describedin greater detail in U.S. Pat. No. 6,159,368, which is incorporatedherein in its entirety by reference.

In one preferred embodiment, shown in the exploded view of FIG. 6, suchsupportive structure takes the form of three fin-like supportbuttresses, denoted as 58 a-58 c, positioned radially and spacedequidistantly within the cavity of drip-director 16 about central outletport 16 c. It should be appreciated that any other reasonable number ofsupport buttresses, e.g., 4 or 6, may be employed instead. Smallportions of the lower surface of filter element 8 a rest on top ofelongated, narrow, uppermost surfaces or edges of the support buttresses58 a-58 c. In the illustrated embodiment, the support buttresses 58 a-58c are formed integrally with the drip director 16.

Greater details about the discharge-conduit array and methods ofmanufacturing the array are described in U.S. Pat. No. 6,159,368, whichis incorporated herein in its entirety by reference.

A further aspect of the present invention pertains to a multi-wellmicrofiltration arrangement that provides for the flow of filtrate outof each well, while avoiding cross-contamination due to aerosols orsplattering.

As previously described, the receiving-well array corresponds to thedrip-director array, with each drip director disposed directly over areceiving or collection well. The receiving-well plate, in turn, isadapted to fit within an open reservoir of a lower vacuum chamber, withthe receiving wells extending down into the reservoir. Upon establishinga suitable vacuum in the lower chamber, filtrate will flow from eachmicrofiltration well and into corresponding receiving wells. Inaccordance with this aspect of the invention, means are provided fordiscouraging filtrate-associated aerosols and residues present at anyone well from traveling to, and potentially contaminating neighboringwells. Such means can include, for example, a cross-flow restrictor,also referred to as an aerosol guard, comprised of a substantiallyaerosol-impervious material, interposed in the region between the uppersurface of receiving plate and the lower surface of drip-director plate.While limiting the passage of aerosols and filtrate-associated residues,the cross-flow restrictor is adapted to permit a vacuum to be drawntherethrough.

With particular reference to the embodiment of FIGS. 2 and 3, asheet-like cross-flow restrictor 30 is provided with an array ofpassages 32 complementary to the receiving well array and drip-directorarray that permit filtrate to pass from each microfiltration well 18 toa corresponding receiving well 26. Except for such passages, cross-flowrestrictor 30 substantially fills the area between the confronting facesof the drip-director and receiving-well plates (14, 24). In this way,well-to-well movement of aerosols over the receiving plate 24 issubstantially blocked. Consequently, the risk of cross-contaminationpresented by aerosol movement is substantially reduced. Additionally,aerosols formed at any one receiving well that inadvertently passthrough the cross-flow restrictor (i.e., those that are not effectivelyblocked or trapped) will be pulled by the vacuum source through anadjacent aperture 28 down to the region below plate 24 without passingover the openings of neighboring receiving wells, as described morefully below.

Greater details about the cross-flow restrictor, methods of attachingthe cross-flow restrictor, and materials useful for the restrictor, aredescribed in U.S. Pat. No. 6,159,368, which is incorporated herein inits entirety by reference.

In another embodiment, the means for avoiding cross-contamination due tothe well-to-well movement of aerosols includes vents or apertures 28extending through the surface of receiving plate 24. In one preferredembodiment, at least one such aperture is disposed near each receivingwell. It should be appreciated that a reduced pressure applied frombelow the plate will extend through the apertures to the microfiltrationwells.

Greater details about the number of, positioning, and othercharacteristics about the aperatures can be found in U.S. Pat. No.6,159,368, which is incorporated herein in its entirety by reference.

As previously noted, apertures 28 permit fluid communication between theregions above and below the receiving-well plate 24. Upon evacuatinglower vacuum chamber 29, a vacuum will be established reaching from exitport 51 to the region between each microfiltration well and acorresponding receiving well. Particularly, the vacuum will pull alongflow pathways extending from each microfiltration well 18 into theinterface region between the confronting surfaces of drip-director plate14 and receiving-well plate 24. The vacuum flow pathways then will crossdownward through the surface 25 of the receiving plate, by way ofrespective vents 28, to the open reservoir of chamber 29. Here, thevacuum flow pathways will extend along the lower chamber until reachingexit port 51. Large, blackened arrows illustrate exemplary vacuum flowpathways in FIG. 3. Advantageously, aerosols and filtrate residues thatbecome entrained in the vacuum flow are largely directed away from eachreceiving well area and out of the system without passing overneighboring receiving wells. Also, it should be appreciated that thevacuum pathways are directed in such a manner as to encourage a flowthat is largely downward and laminar in nature. Cross-flow, and thusturbulence, is greatly minimized compared to most conventionalarrangements.

The illustrated embodiments show a cross-flow restrictor 30 used incombination with a vented receiving-well plate 24, as just described.Notably, the cross-flow restrictor 30 covers the apertures 28, so that avacuum pathway extending from the region between each microfiltrationwell 18 and corresponding receiving well 26 to the region below thereceiving-well plate 24, via a nearby aperture 28, must pass through thecross-flow restrictor 30. Since the cross-flow restrictor 30 allows avacuum to be drawn therethrough, but discourages the passage ofaerosols, filtrate-associated aerosols are substantially separated(i.e., filtered out by the cross-flow restrictor) from the drawn vacuumand, thus, the potential for well-to-well movement of aerosols over thesurface 25 of the receiving plate is even further reduced.

Greater details about using individual cross-flow constrictors can befound in U.S. Pat. No. 6,159,368, which is incorporated herein in itsentirety by reference.

As previously mentioned, it is noteworthy that the vacuum flow pathwaysestablished between the regions above and below the receiving-wellplate, in all of the embodiments described herein, are routed in amanner that encourages a largely laminar and downward flow (includingany entrained gases and/or aerosols). Compared to most conventionalarrangements, horizontal flow over the upper surface of thereceiving-well plate is greatly minimized. Not only is this the case inthe regions proximate the microfiltration and receiving wells, but it isalso the case for the peripheral-edge regions of the plates. In thisregard, and with particular reference to the embodiment of FIG. 3, thecontact between the inwardly extending flap 44 a of stepped gasket 44and the top of ridge 48 of the receiving-well plate 24 is such thatairflow therebetween is obstructed or baffled. Thus, upon evacuating thelower vacuum chamber 29, gases located above the stepped gasket 44, inthe region denoted by arrow 46, will be drawn into the lower vacuumchamber via vent 28. Gases in the space under the lower surface ofstepped gasket 44, denoted generally by the arrow 47, on the other hand,will be drawn into the lower vacuum chamber via a gap 49 providedbetween the receiving-well plate and the surface 50 about vacuum chamber29. By limiting the extent of horizontal airflow across thereceiving-well plate in this way, turbulence resulting from cross flowalong the periphery of the arrangement is minimized.

An additional means for avoiding cross-contamination due to well-to-wellmovement of aerosols, as well as filtrate splattering, relates to thepositioning of each drip director's lower opening relative to the upperrim, or lip, of a corresponding receiving well. According to thisfeature, the outlet port 16 c of each drip director 16 extendsdownwardly from the drip-director plate 14 so as to enter into acorresponding receiving well 26. In this regard, the lower portion ofeach drip director 16 has a diameter that enables it to register withthe open top of a corresponding receiving well 26 in the receiving plate24. As shown in the embodiment of FIG. 3, the outlet port 16 c of eachdrip director 16 is situated below the upper rim or lip of acorresponding receiving well 26. By placing the outlet port 16 c at aregion that is laterally surrounded by the inner sidewalls of thereceiving well 26, much of the aerosol generated during filtration willimpact upon the receiving-well walls, as opposed moving laterally overtoward a neighboring receiving well. As an additional advantage, suchplacement of the drip-director outlets helps to reduce filtratesplattering.

According to various embodiments of the present invention, the presentinvention provides a method for avoiding cross-contamination due towell-to-well movement of aerosols in a multi-well microfiltrationsystem. Greater details about such methods that draw a vacuum downwardto avoid or minimize well-to-well movement are provided in U.S. Pat. No.6,159,368, which is incorporated herein in its entirety by reference. Itshould be appreciated that the apparatus described above is particularlywell suited for carrying out such methods. For example, a vacuumchamber, such as lower chamber 29 shown in FIG. 3, may be connected to alow pressure source, such as a vacuum pump (not shown), for establishinga pressure differential across filter elements 8 a, 8 b disposed inmicrofiltration wells 18. The reduced pressure, then, will causefiltrate to emanate from drip directors 16. Aerosol guard 30 provides ameans to limit filtrate-associated aerosols formed from the filtrate atany one microfiltration well 18 from moving across the upper surface 25of receiving-well plate 24 to a neighboring receiving well. Apertures28, extending through the surface 25 of receiving-well plate 24, permitthe vacuum to extend between each microfiltration well and the regionbelow the receiving-well plate 24 without having to pass over theopenings of neighboring receiving wells.

When evacuating the lower chamber, it is advantageous to slowly change(ramp) the pressure to a desired value, combined with the utilization ofvery low pressures (e.g., less than about 2 psi, and preferably lessthan about 1 psi), to further reduce the potential forcross-contamination, as by aerosols. For example, in going from ambientpressure to a value within the range of about 0.75 to about 2 psi, aramp period of about 2-3 seconds is employed.

According to various embodiments of the present invention, a multi-wellmicrofiltration arrangement is provided for enabling the flow offiltrate from each well, while avoiding cross-contamination due topendent drops that may adhere to the drip directors of the variousmicrofiltration wells. As previously mentioned, such pendent drops canfall into neighboring receiving wells when moving the discharge-conduitarray or drip-director plate over the receiving array or receiving-wellplate.

According to one embodiment, a microfiltration well is evacuated in thedirection of its upper opening, thereby pulling any pendent drops offluid hanging from its drip director back up into the well. Toaccomplish the evacuation, a pressure control source, e.g., a vacuumpump, in communication with an upper region of the mini-column isoperable to evacuate the mini-column in the direction extending from thedrip director to the upper opening.

According to various embodiments of the present invention, pendent dropshanging for the drip directors or discharge conduits are touched-off,whereby the pendent drops are moved to make contact with inner sidewallsof receiving wells or receiving holes of the receiving array. In thisregard, the drip director outlets of all the microfiltration wells aresimultaneously brought into contact with the inner sidewalls ofcorresponding receiving wells.

Means are provided for effecting relative movement between thedischarge-conduit array or drip-director plate, and the receiving arrayor receiving-well plate, for simultaneously moving the dischargeconduits proximal to, or into contact with, and distal from or out ofcontact with, the inner walls of the respective receiving wells orreceiving holes.

According to various embodiments of the present invention, a device isprovided for shifting the receiving array along a plane substantiallyorthogonal to the longitudinal axes of the receiving wells or receivingholes of the receiving array, while the discharge conduits aremaintained in a substantially fixed position. In other variousembodiments, the device for effecting relative movement is operable toshift the discharge-conduit array along a plane substantially orthogonalto the longitudinal axes of the receiving wells or receiving holes ofthe receiving array, while the receiving wells are maintained in asubstantially fixed position.

An exemplary arrangement for effecting relative movement is depicted inFIGS. 7 through 10. With initial reference to FIGS. 7 and 8, an L-shapedcarriage, as denoted by the reference numeral 60, is provided with acentral opening 62 configured to receive and support a multi-wellmicrofiltration assembly, indicated generally as 6, from above. Belowcarriage 60, a receiving-well plate 24 having an array of receivingwells 26 is supported in a lower vacuum chamber (not shown).

Carriage 60 is mounted on a pair of parallel longitudinal carrier railsfor reciprocal linear movement along a first, substantially horizontal,axis. In the illustrated embodiment, one of the carrier rails is alinear bearing rail, denoted as 64, which supports the carriage 60 viaan interposed linear bearing member 65 attached to the lower surface ofthe carriage 60 toward one lateral edge. The other carrier rail is aU-shaped bearing guide, denoted as 66, that receives a bearing wheel 68,extending laterally outward from the other edge of the carriage 60, inan elongated track or slot 66 a.

Carriage 60 is moved along the rails 64, 66 by a belt assembly comprisedof a flexible belt 70 having its ends attached at each longitudinal endof a U-shaped bracket 74 forming a part of a spring-loadedmovement-control mechanism 72, described more fully below. Belt 70 ispassed around a driven roller 76 and an idler roller 78, disposedproximate longitudinally opposing ends of the carrier rail arrangement.To prevent against slippage, the belt may be provided with teeth 70 aadapted for mating engagement with complementary sets of teeth 76 a, 78a on the rollers.

Driven roller 76 is in mechanical communication with a motor, such as82, through a power train assembly, as indicated generally by thereference numeral 84. When motor 82 is energized, belt 70 will move,causing carriage 60 to slide along the carrier rails 64, 66, with thedirection of movement depending on the rotation of the drive shaft 86extending from motor 82. Motor 82 may be of any suitable, known type,e.g., a stepper motor, servo motor, or similar device. In place of themotor, a manually operable drive system can be used for providingmovement of the various components along respective paths to accomplishtouch-off and transfer operations. In various manually-operableembodiments of the present invention, the motor is replaced with amanually-operable handle that actuates the roller, for example, througha transmission system, wherein the handle can be a lever, two or morelevers, a bar, a knob, or any other suitable manually-operable actuator.

Stepping the motor 82 causes belt 70 to move around rollers 76, 78, withthe direction of movement dependent upon the direction of rotation ofthe motor's shaft 86. Movement of belt 70, in turn, causes carriage 60to slide along guide rails 64, 66, thereby shifting the drip directorarray 16 laterally with the respect to the receiving well array 26. Ifthe drip directors 16 are positioned so that they extend into respectivereceiving wells 26, sufficient stepping in a given direction will causethe drip directors 16 to engage the upper, inner surfaces of thereceiving wells 26, as shown in the sectional views of FIGS. 9(A)-9(C).In this way, pendent drops of filtrate hanging from the drip directors16 are “touched off” to the inner surfaces of respective receiving wells26. Similarly, upon reversing the stepping direction, the drip directors16 can be moved to engage the upper, inner surfaces on the opposing sideof the receiving wells 26 to further ensure effective touching-off ofpendent drops. Greater details about motorized operation of thetouch-off devices according to various embodiments of the presentinvention can be found in U.S. Pat. No. 6,159,368, which is incorporatedherein in its entirety by reference.

Carriage additionally supports means for moving and positioning themicrofiltration arrangement 6 along a second, generally vertical, axis.With particular reference to the embodiment of FIG. 7, avertical-positioning mechanism is disposed on the upper surface ofcarriage along each lateral side of the microfiltration arrangment. Eachvertical-positioning mechanism includes (i) lift springs, such as 92,that provide a continuous, upwardly-directed force tending to raise themicrofiltration arrangement 6 to an elevated position whereat the dripdirectors 16 fully clear the upper lips of the receiving wells 26, and(ii) fluid cylinders, such as 94, that are operable to lower themicrofiltration arrangement 6, against the force of the lift springs 92,to a seated position whereat each drip director 16 extends into theupper region of a respective receiving well 26. At its fully seated(lowered) position, the microfiltration arrangement 6 forms a seal withthe lower vacuum chamber (not shown).

Both the springs 92 and the fluid cylinders 94 engage, at their upperends, handles, denoted as 96, that extend upwardly and outwardly fromeach lateral side of the microfiltration arrangement's supporting frame38. In one embodiment, the spring/cylinder arrangements are operable tohold the microfiltration arrangement at any one of three positions: (i)an open, upper, or travel position, (ii) an intermediate touch-offposition, and (iii) a sealed or lower position. Manually-operablevertical positioning systems can be used and are described in moredetail below.

Another exemplary arrangement for effecting relative movement of thedischarge conduits and the receiving wells or receiving holes isdepicted in FIGS. 11-17. According to various embodiments of a deviceaccording to the present invention, a means or device for effecting therelative movement is provided. The device includes a manually-operablemechanism, referred to herein as a handle, to shift thedischarge-conduit array, or alternatively, the receiving array, relativeto the other along a plane substantially orthogonal to the longitudinalaxes of the discharge conduits. The handle can be a locking two-leverhandle, for example. In such an embodiment, an operator places thedischarge-conduit array or purification tray into the microfiltrationapparatus while the apparatus is in the open position shown in FIG. 11.The operator then depresses the handle to thereby bring the discharge ordistal ends of the discharge conduits to a point below the plane of theupper opening of the respective receiving wells. In this position, thedistal ends of the discharge conduits, or the purification tray of whichthey are a part, can be manually shifted as described herein byapplication of a manual force to a handle connected to thedischarge-conduit array. The movement of the handle can effect atouching-off operation, a vacuum sealing operation, a release operation,a station shift operation, or the like. The touch-off is accomplished,for example, by causing pendent drops of fluid hanging from the distalends of the discharge conduits to contact the inner sidewalls of thereceiving wells. The shifting can be done in a single movement, a doublemovement, or multiple movements, depending on the choice of the operatorand the particular properties of the filtrate, such as viscosity, or theamount of precipitate present.

According to various embodiments of the present invention, it is notnecessary for the distal ends of the discharge conduits to physicallytouch the sidewalls of the receiving wells, if the pendent drops contactthe inner sidewalls of the receiving wells. The important aspect ofthese embodiments of the present invention is to achieve the completetransfer of each drop into the correct receiving well, and breaking thesurface tension of the drop may be sufficient to achieve a gentletransfer without requiring the drip director or discharge conduit itselfto touch the inner sidewall of the respective receiving well. Accordingto various embodiments of the present invention, “touching-off” refersto contacting of the pendent drops alone to the sidewalls of thereceiving wells. According to various embodiments of the presentinvention, touching-off refers to contacting the distal tips of thedischarge conduits and touching the pendent drops to the correspondinginner sidewalls.

The touching-off (also referred to herein as the “touch-off operation”)is illustrated in FIGS. 9A, 9B, and 9C. In FIG. 9A, the distal ends ofthe discharge conduits (also referred to herein as the drip directors)are shown positioned in the center of and above the correspondingreceiving wells. In FIG. 9B, the distal ends of the discharge conduitsare shown in contact with the right side of the corresponding receivingwells. In FIG. 9C, the distal ends of the discharge conduits are shownin contact with the left side of the corresponding receiving wells.Thus, according to an embodiment of the present invention, thepurification tray or array of discharge conduits can be manuallytranslocated from the position illustrated in FIG. 9A to the positionillustrated in FIG. 9B to initiate the touching-off operation. The arrayof discharge conduits can then be manually translocated from theposition illustrated in FIG. 9B to the position illustrated in FIG. 9Cto continue and eventually complete the manual touching-off operation.

The touch-off operation may be carried out with the microfiltrationarrangement 6 disposed at any position along the second (vertical) axis,provided only that the drip directors 16 extend at least partially downinto the receiving wells 26. In one embodiment, touching-off of the dripdirectors 16 to the inner sidewalls of the receiving wells 26 iseffected with the microfiltration arrangement 6 slightly raised aboveits fully seated position so that the lowermost regions of the dripdirectors 16, proximate their outlets 16 c, will abut the inner surfacesof the receiving wells 26.

Thus, in an embodiment of the present invention is presented adischarge-conduit array including an array having a first plate having aplurality of columns, each column having a filter medium and beingpositioned over a second plate having a plurality of discharge conduits,whereby the discharge-conduit array is placed in a microfiltrationapparatus of the present invention including a plurality of receivingwells, each receiving well positioned to receive filtrate from acorresponding distal ends of the discharge conduits, and whereby thedischarge-conduit array is manually translocated in a generallyhorizontal manner in either of two directions from a reference “home”position along a generally horizontally extending axis, and then thedischarge-conduit array is returned back to the reference “home”position, such that manual touching-off is achieved.

The region of each drip director 16 proximate its outlet may be shaped,e.g., angled or chamfered about its lower circumference, to promote thelocalization of any pendent drops of filtrate to certain regions of thedrip director 16 and to optimize contact between such regions with theinner sidewall of a corresponding receiving well 26 during touch off.Similarly, the upper region of each receiving well 26 may also beshaped, e.g., in a manner complementary to (i.e., matching) a shapeddrip director 16, so that adequate contact is made between theseelements during touch off for substantially ridding the drip director 16of any pendent drops of filtrate. In one preferred embodiment, as can beseen in FIGS. 9A-C, the upper, region of each receiving well is formedwith an outwardly angled inner sidewall that matches an inwardly angledouter surface along the lower region of a corresponding drip director,thereby providing a substantial abutting surface between these elementsduring a touch-off necessary. That is, the drip directors 16 might bemoved into engagement with the inner walls of the receiving wells 26,with continued pressure to move beyond the inner walls. Greater detailsabout motorized control of the touch-off procedure and overshootconsiderations are described in U.S. Pat. No. 6,159,368, which isincorporated herein in its entirety by reference.

In one embodiment, the movement-control mechanism includes a springdisposed such that movement of the carriage in either direction alongthe first axis will put the spring under compression. With particularreference to the partially schematic top plan views of FIGS. 10(A)-(C),the U-shaped bracket 74 that forms a part of the belt assembly isrigidly connected to a housing 101 containing large and small bores,respectively indicated generally as 102 and 108. Bore 102 has alarge-diameter portion 102 a and a small-diameter portion 102 b,separated by a radial step 102 c. A stepped-diameter shaft, indicatedgenerally as 104, having a large-diameter portion 104 a and asmall-diameter portion 104 b, separated by a radial step 104 c, passesthrough bore 102 and rigidly attaches, at its large-diameter end, to anextended-arm portion 60 a of the L-shaped carriage 60. A guide pin 106,which assists in maintaining the substantially horizontal orientation ofcarriage 60, rigidly attaches to the extended arm portion 60 a ofcarriage 60 at one end and is received in small bore 108 at its otherend. Inside the large-diameter portion 102 a of bore 102, a spring 110concentrically mounts the small-diameter portion 104 b of shaft 104between a pair of spaced washers, denoted as 112 and 116. The twowashers 112, 116 are concentrically mounted for sliding movement alongthe small-diameter portion 104 b of stepped shaft 104. Spring 110 urgesthe two washers 112, 116 toward opposite, extreme ends of thesmall-diameter portion 104 b of shaft 104. A fixed-position washer 114is seated within a circumferential groove (not shown) formed in thesmall-diameter portion 104 b of shaft 104 near its free end.

When belt 70 moves U-shaped bracket 74 in the direction indicated by thearrow “A,” in FIG. 10B, bore 102 slides along shaft 104 in a directiontoward the extended arm 60 a of carriage 60. As a result, an annular lip120 that extends radially inward at the end of bore 102 acts against anannular, peripheral region of washer 112, causing the washer 112 toslide along the small-diameter portion 104 b of stepped shaft 104,thereby compressing spring 110. When the compression force overcomes thepre-loaded retaining force, carriage 60 will then shift in the samedirection (direction “A”).

When belt 70 moves U-shaped bracket 74 in the direction indicated by thearrow “B,” in FIG. 10C, bore 102 slides along shaft 104 in a directionaway from the extended arm 60 a of carriage 60. As a result, the radialstep 102 c of bore 102 acts against an annular, peripheral region ofwasher 116, causing the washer 116 to slide along the small-diameterportion 104 b of stepped shaft 104, thereby compressing spring 110. Whenthe compression force overcomes the pre-loaded retaining force, carriage60 will then shift in the same direction (i.e., direction “B”).

In an embodiment, spring 110 provides a pre-load force of about 1 pound.Thus, the force provided by the stepper motor 82 will not be effectiveto move the carriage 60 until the threshold of about 1 pound isovercome. Advantageously, the arrangement provides (i) a constant-holdmode at the center, or neutral, position, and (ii) a constant-force modefor effecting touch off. The spring 110 provides compliance in thesystem, e.g., allowing touch-off to start at 1 pound and end at 1.2pounds.

With reference to the apparatus as described above, one preferredembodiment of the present invention contemplates the following steps:

(i) microfiltration arrangement 6 is loaded onto carriage 60 and clampedin place;

(ii) carriage 60 is centered over a lower vacuum chamber 29;

(iii) microfiltration arrangement 6 is lowered to its seated position(e.g., by retracting fluid cylinders 94) and sealed over the lowervacuum chamber 29;

(iv) a vertical positioning apparatus or system (not shown) lowers uppervacuum chamber 20 against the top of microfiltration arrangement 6 and,optionally, applies a downward force, e.g., about 5 pounds, to thestacked arrangement;

(v) lower vacuum chamber 29 is evacuated (e.g., at about 0.5-3 psi) toeffect elution/purification;

(vi) carriage 60 is raised slightly from its fully seated position to atouch-off height whereat only the lowermost regions of the dripdirectors 16 extend below the upper lips of the receiving wells 26;

(vii) a manually-operated drive device is used to move the dripdirectors in a forward direction to touch off the drip directors 16 to asidewall of the receiving wells 26;

(viii) the manually-operated drive device is used to move the dripdirectors in a reverse direction to touch off the drip directors 16 tothe opposing inner sidewalls of the receiving wells 26;

(ix) forward and reverse movements are repeated to perform each of thetouch-off steps once more;

(x) carriage 60 is re-centered over lower vacuum chamber 29;

(xi) microfiltration arrangement 6 is lowered to its seated position andsealed over lower vacuum chamber 29;

(xii) optionally, a downward force of, for example, about 5 pounds, canbe applied to the stacked arrangement;

(xiii) upper vacuum chamber 20 is evacuated to effect a pull-back ofpendent drops (e.g., at about 0.1-0.3 psi);

(xiv) microfiltration arrangement 6 is raised to its fully elevatedposition so that the drip directors 16 fully clear the receiving wells26; then

(xv) carriage 60 is moved to next station.

FIG. 16 of U.S. Pat. No. 6,159,368 shows an automated work station tocarry out these steps in an automated fashion.

Also useful as part of the microfiltration apparatus of the presentinvention is software containing a software program, and asoftware-reading device or software-implementing means, within orexternally connected to the microfiltration apparatus, wherein thesoftware contains at least one algorithm which can control through thesoftware-reading device or software-implementing means the pressuredifferential operations of the apparatus. In an embodiment of thepresent invention, embedded software controls all differential pressureoperations, such as vacuum and positive pressure operations, to therebyprecisely set at least a pressure differential or partial vacuum aboveor below the distal ends of the discharge conduits, the duration of thepartial vacuum, and pressure levels, control start and stop actions,allow the operator to create individualized methods, specify users,display run logs on a digital or visual display, and diagnose thesystem. The software can be programmed to allow the operator of themicrofiltration apparatus to store in the memory of the software-readingdevice methods and conditions for future reference, repetition, and/ormodification.

With regard to spatial orientation, it should be noted at this pointthat the various components (e.g., upper chamber, mini-column plate,filter element, drip-director plate, frame, cross-flow restrictor,receiving-well plate, and lower chamber) are illustrated and describedherein as being stacked in vertical relationship, with the upper vacuumchamber being the topmost component. Further, each microfiltration wellis described as having a central axis disposed in a substantiallyvertical fashion, with a flow pathway extending downwardly through thewell. It should be noted, however, that these orientations have beenadopted merely for convenience in setting forth the detaileddescription, and to facilitate an understanding of the invention. Inpractice, the invention contemplates that the components and wells maybe disposed in any orientation.

Methods of covering and sealing receiving arrays, for example, can befound in U.S. Pat. No. 6,159,368, which is incorporated herein in itsentirety by reference, particularly in FIGS. 11-14 of the patent.Automated handling and work stations to carry out many of theaforementioned and/or additional methods are described in greater detailin U.S. Pat. No. 6,159,368, particularly with respect to FIGS. 16-24 ofthe patent.

According to various embodiments of the present invention, the features,relationships of arrays, and touch-off methods described herein,particularly above, are used in a manually-operated workstation, inparticular, to provide a manually-operable multi-well microfiltrationapparatus and method. Exemplary manually-operable apparatus according tovarious embodiments of the present invention are shown in FIGS. 11-27.

According to various embodiments of the present invention, thedischarge-conduit array and the corresponding carriage of the device canoccupy at least three vertical positions, for example, an open position,a sealed position, and a touch-off position. The open position is shown,for example, in FIGS. 11, 19, 22, and 25, which depict a multi-wellmicrofiltration apparatus according to various embodiments of thepresent invention. In the open position, a discharge-conduit array withsamples can be loaded into or removed from the apparatus. As can beseen, the distal tips 570 of the discharge conduits 510 of thedischarge-conduit array 500 horizontally clear the receiving wells 502of a receiving well array 590. FIG. 11 is a partial side cross-sectionalview in partial breakaway of a device 499 according to an embodiment ofthe present invention with a discharge-conduit array 500 in a beginningor open position. The relationship between the discharge-conduit arrayand the receiving array can be seen, for example, in greater detail withreference to FIGS. 24-26, particularly in FIG. 25 which depicts the openposition. In the open position, shown enlarged in FIG. 25, a gap 551exists between the bottom 562 of a deformable apron 517 on thedischarge-conduit array carriage 500, and the top surface 564 of areceiving array platform 566. The distance between the discharge conduitarray 500 and the receiving array 590 enables the discharge-conduitarray 500 to move horizontally and clear the receiving array 590. Thisdistance is eliminated when the apparatus is in the sealed position, asshown, for example, in FIGS. 13, 16, 20, 23, and 26. The touch-offposition is exemplified in FIGS. 12, 14, 15, 17, 18, 21, 24 a, 24 b, and27.

Many of FIGS. 11-27 depict apparatus including two or more treatmentstations. FIG. 11, for example, shows a discharge-conduit array carriageassembly 600 positioned to axially align the discharge conduits 510 ofthe discharge-conduit array 500 with corresponding receiving wells 502of a receiving well array 590, at a first treatment station 610.According to various embodiments of the present invention, the dischargeconduit array can be shifted while in the open position, with thecarriage assembly 600, to align the discharge-conduit array with asecond receiving array 592 of receiving wells 508 at a second treatmentstation 612. The carriage assembly 600 can be moved from the firsttreatment station 610 to the second treatment station 612, and back tostation 610, as for example, by a sliding engagement with a rail ortrack 506 from station 610 to station 612.

Station 610 can be useful, for example, for archiving, collecting, orfiltering samples. Station 612 can be useful, for example, for washingmaterial from a sample, disposing of undesirable material, and/orcollecting waste from a sample or samples. As such, station 612 can beconnected to a waste receptacle able to receive waste that is expelledfrom the distal ends 570 of the discharge conduits 510 and into thewaste receiving wells 508.

FIG. 11 depicts an open position of the device with the distal ends 570of the discharge conduits 510 of the discharge-conduit array 500positioned above and outside the upper opening of the respectivereceiving wells 502. In this open position, of the device according toan embodiment of the present invention, the discharge-conduit array 500can be manually moved along track 506 to the station 612 and alignedover the receiving wells 508.

The handle 504 shown in the drawings is provided with a releasablemechanism to lock the handle in the open or sealed positions. The Figs.also show a secondary clamp 512 for locking the carriage in theintermediate position.

The Figures, including FIGS. 21-23, illustrate the operation of thetwo-levered, manually-operable handle and its relationship to thevertical positioning assembly 501. In the open position shown in FIGS.22 and 25, the two-levered handle is up and secondary clamp 512 isreleased from latch 514. When both the handle 504 and connecting arm 530of secondary clamp 512 are depressed sufficiently, a locking mechanismin conjunction with catch arm 642 latches the vertical positioningassembly in a fully depressed position for vacuum discharge. Squeezingrelease mechanism 505 toward handle 504 releases the locking mechanismin conjunction with catch arm 642 and allows the handle 504 to be liftedto an elevated position. When the handle 504 is in the elevated positionand vertical positioning assembly 501 is in the touch-off position, thesecondary clamp 512 is not released from latch 514 such that thevertical positioning assembly 501 and the discharge-conduit array 500are positioned with the discharge conduit nozzle tips at or just insidethe open upper ends of the respective receiving wells, and slightlyelevated with respect to their positions in the closed or sealedposition. Activation of latch 609 releases latch 514 from secondaryclamp 512 and enables the vertical positioning assembly 501 and thedischarge conduit array to be lifted to an even further elevated open orstation transfer position. In operation, handle 504 pivots about pivotpoint 520, whereby handle 504 can be raised to set the discharge-conduitarray 500 in position for manual touching-off. No touching-off can occurin the open position depicted in FIG. 11 because the distal ends 570(drip directors) of the discharge conduits 510 are not positioned withinor near the openings of the receiving wells 502.

A biasing device 507, such as a torsion spring or compression spring, inmechanical communication with a release mechanism 505 within the handle504, biases the handle 504 into a locked position whereby thedischarge-conduit array 500 cannot be shifted. In response to acompressive manual force applied by an operator to the release mechanism505 and against the bias of the biasing means 507, the locked positionof the handle 504 is disengaged. The release mechanism 505 works totransmit a force through an arm 642 as shown, for example, in FIGS. 21and 27 to a vertical positioning assembly lock release position.Activating the release mechanism 505 allows the handle 504 to beelevated to an elevated position, whereby the carriage can be moved intoan intermediate touch-off position. Once in the elevated position, thehandle 504 can then be manually pushed and pulled for touch-off. Fromthe touch-off elevated handle position, the release mechanism 609 can beactivated to release a second lock or a second release mechanism, tounlock or release the carriage, resulting in a freedom of the carriageto move into an elevated, beginning, open, release position, forexample, against a biasing mechanism. Handle 504 pivots about pivotpoint 520 allowing handle 504 to be raised and lowered.

In operation, handle 504 is manually gripped by an operator of themicrofiltration apparatus. The manually-applied horizontal force can beused to horizontally shift the discharge-conduit array 500, for example,for a touch-off operation. Additionally, or in the alternative, thedischarge-conduit array 500 can be released to permit manual moving byan operator from the first station 610 to the second station 612.

FIG. 12 is a partial side cross-sectional view in partial breakaway of adevice 499 according to an embodiment of the present invention havingthe discharge-conduit array 500 in the touch-off position. In FIG. 12,the discharge-conduit array 500 is located at station 610 above thereceiving wells 502. Touching-off can also be performed when thedischarge-conduit array 500 of FIG. 12, is located at station 612. InFIG. 12, the handle 504 is in the raised position and the secondaryclamp 512 is in the lowered and secured position. The distal ends of thedischarge conduits 510 of the discharge-conduit array 500 are positioneddirectly above the receiving wells 502 and extending below the upperplane defining the upper openings of the respective receiving wells 502.

In any suitable position the discharge-conduit array 500 can receivereactants, such as DNA materials, reagents, lysing agents, and the like.After a pressure differential, if any, is applied, the discharge-conduitarray 500 can be manually advanced slightly by sliding thedischarge-conduit array 500 in a direction toward the right in FIG. 12,then manually retracted by pulling the handle 504 connected to thedischarge-conduit array 500 backward to the left in FIG. 12. The extentof the movement or translocation of the discharge-conduit array 500, thedistance is limited by the contacting of, or a provision not to contact,the distal ends 570 of the discharge conduits 510 with the innersidewalls 602 of the receiving wells 502, 508 or 524. Gap 550 is muchsmaller in the touch-off position of FIG. 12 than the gap 551 shown inthe open position of FIG. 11. Gap 550 in the touch-off position of FIG.14, can be, for example, from about 0.01 inch to about 0.1 inch, forexample, about 0.07 inch.

FIG. 13 is a partial side cross-sectional view in partial breakaway of adevice 499 of an embodiment of the present invention with thedischarge-conduit array 500 in the sealed position. In this position,the secondary clamp 512 and handle 504 are in a lowered, engaged andsealed position, whereby the discharge-conduit array 500 is positionedabove the receiving wells 502 such that the distal ends of the dischargeconduits 510 are each directly above and within the circumference of theopenings of the receiving wells 502. Thus, while the discharge-conduitarray 500 is in this sealed position, a pressure differential, such asat least a partial vacuum, can be applied to the volume beneath thereceiving wells 502, whereby the fluid in the distal ends of thedischarge conduits 510 is urged downward through a filter medium 518.Touching-off may be disabled while the discharge-conduit array 500 is inthe sealed position.

FIG. 13 shows a latch 514 that engages and secures secondary clamp 512in the lowered and sealed position. Secondary clamp 512 can be manuallyreleased from latch 514. Handle 504 pivots about pivot point 520allowing handle 504 to be raised and lowered. A seal replaces gaps 550and 551 and is effected by the contact of a deformable apron 517 withthe top surface 564, also referred to as deckspace 519, of platform 566.The deformable apron 517 can be compressed between components of thecarriage assembly 600, or between the discharging and the receivingarrays. The deformable apron 517 can be, for example, a gasket or asuction cup-like device made of natural or silicone rubber.

FIG. 14 is an enlarged detailed cross-sectional view of a deviceaccording to an embodiment of the present invention showing thedischarge-conduit array 500 and deep receiving wells 582 in thetouch-off position. A detent 503 can be provided for horizontallyaligning the discharge-conduit array in the vertical positioningassembly 501. The detent 503 can include a rubber or elastomericmaterial. In FIG. 14, the discharge-conduit array 500 is not tightlysealed to the top of the receiving well 590, however, the distal ends ofthe discharge conduits 510 of the discharge-conduit array 500 aresufficiently below the top of the receiving well array 590 and able tocontact the inner sidewalls of the deep receiving wells 582. A space “e”is shown between the bottom of the discharge-conduit array 500 and thetop of the receiving well array 590, indicating the discharge-conduitarray 500 is in the touch-off position. Filter medium 518 is positionedwithin each discharge conduit 510. Deep receiving wells 582 are depictedin FIG. 14, but microwells 524 can also be substituted for the deepreceiving wells 582, as shown in FIG. 15. Suitable adapters can be usedto adjust height requirements and size requirements of the variousarrays.

Deep receiving wells can be, for example, from about 800 microliters toabout 1 milliliter, and the microwells can be, for example, from about100 to about 500 microliters.

FIG. 15 is an enlarged detailed cross-sectional view of a deviceaccording to an embodiment of the present invention showing thedischarge-conduit array 500 and discharge-conduit array and shallowreceiving wells 524. FIG. 15 shows a side cross-sectional view of anembodiment of a microfiltration apparatus of the present invention inthe touch-off position, wherein the receiving wells are shown asmicrowells 524, as opposed to larger wells such as the deep receivingwells 582 shown in FIG. 14. The distal ends of the discharge conduits510 of the discharge-conduit array 500 are positioned above therespective receiving microwells 524. FIG. 15 shows spaces “c” and “d”representing the space for linear translocation or horizontal movementof the discharge-conduit array 500 to achieve touching-off upon exertinga manual force sufficient for horizontal translocation of thedischarge-conduit array 500. Manual movement of the discharge-conduitarray 500 across space “d” causes the distal ends of the dischargeconduits 510 to contact the inner sidewall of the microwell receivingwell 524. A different manual movement of the discharge-conduit arrayacross space “c” causes the distal ends of the discharge conduits 510 tocontact the opposite inner sidewall of the microwell receiving well 524.See also FIGS. 9A, 9B, and 9C.

FIG. 16 is a front cross-sectional view of a device 499 according to anembodiment of the present invention with the discharge-conduit array 500in the sealed position. In this representation, the discharge-conduitarray 500 is positioned in a microfiltration apparatus according to anembodiment in the sealed position. In FIG. 16, the discharge-conduitarray 500 is locked into an archiving, or collection station 610.

FIG. 17 is a front cross-sectional view of a device 499 according to anembodiment of the present invention with the discharge-conduit array 500in the touch-off position. In this representation, the discharge-conduitarray 500 is in a microfiltration apparatus according to an embodimentin the touch-off position. The distal ends 570 of the discharge conduits510 rest just within the upper openings of the corresponding receivingwells 524.

FIG. 18 is a partial cross-sectional view of a device according to anembodiment of the present invention with the discharge-conduit array 500in the touch-off position. The handle 504 is up and the seal around thedeformable gasket 517, which can be, for example, a silicone gasket, hasbeen broken. The drip directors or distal ends of the discharge conduits510 are barely in the receiving wells 502 of the receiving or archiveplate.

FIG. 19 is a partial cross-sectional view of a device according to anembodiment of the present invention with the discharge-conduit array 500in the released or open position. The handle 504 is up, the dripdirectors or distal ends of the discharge conduits 510 are out of thereceiving wells, the deformable apron 517 is lifted, and thedischarge-conduit array 500 is raised and free to move to the secondtreatment station 612 of FIGS. 11-13.

FIG. 20 is a partial cross-sectional view of a device according to anembodiment of the present invention with the discharge-conduit array 500in the sealed or closed position. The handle 504 is down and locked, thedischarge-conduit array 500 is positioned over the receiving wells, thedeformable apron 517 is in contact with the deckspace 519 or top surface564 of the platform 566 to form a seal therewith, and the distal ends ofthe discharge conduits 510 are within the openings of the receivingwells 502.

FIG. 21 is a perspective view of a device according to an embodiment ofthe present invention with the discharge-conduit array 500 in thetouch-off position. The handle 504 is up, and release mechanism 505located in the handle 504 can be manually compressed against a biasingmeans 507 (not seen in FIG. 21). Secondary clamp 512 is engaged withlatch 514. The carriage assembly is provided with one or more retainingdevice or pivotable detent 640 to secure the discharge-conduit array tothe carriage assembly 600. A release lever 609 is provided for releasingthe latch 514 from the secondary clamp 512. FIG. 21 also shows thepivotable detent 640 vertically locking the discharge-conduit array inthe vertical positioning assembly 501 shown in FIGS. 14 and 15.

FIG. 22 is a perspective view of a device according to an embodiment ofthe present invention with the discharge-conduit array 500 in thereleased or open position. The handle 504 is up, and the secondary clamp512 is released from the latch 514.

FIG. 23 is a perspective view of a device according to an embodiment ofthe present invention with the discharge-conduit array 500 in the sealedor closed position. The handle 504 is fully depressed, and thedischarge-conduit array 500 is positioned over the receiving well tray.

FIG. 24 a is a partial cross-sectional view of a device according to anembodiment of the present invention with the discharge-conduit array 500in the touch-off position. The handle 504 is up, the deformable apron517 is not in contact with the deckspace 519 or top surface 564, and agap 550 is provided between the deformable apron 517 and deckspace 519.The distal ends 570 of the discharge conduits 510 are just inside theopenings of the receiving wells 502, and pendent drops are able totouch-off to the inner sidewalls of said receiving wells 502 upon theapplication of a sufficient manual horizontal force applied to thedischarge-conduit array 500 via the handle 504.

FIG. 24 b is a partial cross-sectional view, reverse view to FIG. 24 a,of a device according to an embodiment of the present invention with thedischarge-conduit array 500 in the touch-off position.

FIG. 25 is a partial cross-sectional view of a device according to anembodiment of the present invention with the discharge-conduit array 500in the released or open position. The handle 504 is up, the dripdirectors or distal ends of the discharge conduits 510 are out of thereceiving wells 502, the deformable apron 517 is lifted, and thedischarge-conduit array 500 is raised and free to move to secondtreatment station 612 shown in FIGS. 11-13.

FIG. 26 is a partial cross-sectional view of a device according to anembodiment of the present invention with the discharge-conduit array 500in the sealed or closed position. The handle 504 is down and locked, thedischarge-conduit array 500 is positioned over the receiving wells 502,the deformable apron 517 is in contact with the deckspace 519 or topsurface 564 of platform 566 to form a seal therewith, and the distalends of the discharge conduits 510 are within the upper openings of thereceiving wells 502.

FIG. 27 is a partial side view of a device according to an embodiment ofthe present invention with the discharge-conduit array 500 and carriage,and the handle, in the touch-off positions. The arm 642 is guided inmovement by a sleeve 643.

In various embodiments of the apparatus of the present invention, theapparatus is equipped with the second treatment station 612. Station 612can be used, for example, to transfer waste washed from thedischarge-conduit array station to a waste receptacle. Station 612 canbe provided with a splash guard plate to prevent cross-contaminationbetween receiving wells. When the discharge-conduit array 500 is locatedat station 612, touch-off can be performed, as well as the applicationof pressure differentials, such as vacuum operations, separately, orsimultaneously.

The manual translocation or horizontal movement of the carriage assembly600, and discharge-conduit array 500, according to the present inventiondoes not need to be a large distance for touch-off. The translocationneed only be sufficient to facilitate the touching-off of the pendentdrops from the distal ends of the discharge conduits into the respectivereceiving wells. Thus, the translocation need only be a distanceapproximately equal to or less than, but no greater than, the diameterof the opening of the receiving well into which the distal ends of thedischarge conduits is extended. This can be in an embodiment, forexample, and not as a limitation herein, a distance of from aboutone-sixteenth of an inch up to about one and a half inches. Thetranslocation distance useful in the touching-off operation of thepresent invention is illustrated as spaces “c” and “d” in FIG. 15.

According to various embodiments of the present invention, thedischarge-conduit array can include selected elements shown in FIG. 2.Thus, for example, and not by limitation herein, a usefuldischarge-conduit array according to an embodiment can include elementsnumbered 40, 8 and 14 to form a purification tray of discharge conduitswith drip directors, wherein the purification tray can be manuallytranslocated to achieve touching-off of the distal ends of the dripdirectors to the inner sidewalls of the receiving wells. Other elementsfor incorporation into a discharge-conduit array adapted for manualtranslocation for improved touching-off will be recognized by thoseskilled in the art from the elements described and shown in FIG. 2.

The present invention also provides, according to various embodiments, amethod of purifying a sample in a microfiltration apparatus having anarray of a plurality of discharge conduits each of which contains afiltration medium. The conduits are positioned above an array of aplurality of corresponding receiving wells having inner sidewalls. Themethod includes: providing a fluid sample into the discharge conduits;passing the sample through the filtration medium to produce a filtrate;and manually shifting in a generally horizontal direction the array ofdischarge conduits, whereby the shifting causes pendent drops of fluidhanging from the discharge conduits to contact the inner sidewalls ofthe receiving wells. Various embodiments of the methods of the presentinvention can also be understood with reference to the above descriptionof the apparatus.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention hasbeen described in connection with particular embodiments and examplesthereof, the true scope of the invention should not be so limited.Various changes and modification may be made without departing from thescope of the invention, as defined by the appended claims.

1. An apparatus, comprising: (i) a discharge conduit array comprisingdischarge conduits; (ii) a receiving array comprising receiving wells orreceiving holes; (iii) a carriage configured to carry the dischargeconduit array and adapted for movement along a first, generallyhorizontal, axis from and to a neutral position whereat the dischargeconduit array and the receiving array are substantially axially aligned;(iv) a vertical positioning assembly configured for supporting thedischarge conduit array for movement along a second, generally vertical,axis between (a) a first position whereat the discharge conduits of thedischarge conduit array clear the receiving wells or receiving holes ofthe receiving array, and (b) a second position whereat the dischargeconduits extend down into the receiving wells or receiving holes of thereceiving array; and (v) a manually-operable handle connected to thecarriage and the vertical positioning assembly and configured such thata movement of the handle moves the carriage along the first axis, and asecond movement of handle moves the vertical positioning assembly alongthe second axis.
 2. The apparatus of claim 1, wherein the handle isconfigured for pivotal movement from a beginning position to a setposition, from the set position to an intermediate position, and fromthe intermediate position to a release position.
 3. The apparatus ofclaim 2, wherein the handle includes two or more levers.
 4. Theapparatus of claim 2, wherein the beginning position is an elevatedposition, the set position is a depressed position, and the intermediateposition is intermediate the beginning position and the set position. 5.The apparatus of claim 4, wherein the release position is the same asthe beginning position.
 6. The apparatus of claim 4, wherein thecarriage is connected to the handle such that: when the handle is in theelevated beginning position, the vertical positioning assembly is in theelevated position; and when the handle is in the set position, thevertical positioning assembly is in the lowered position.
 7. Theapparatus of claim 4, further including a releasable lock wherein whenthe handle is depressed into the set position, the releasable lock isadapted to activate and maintain the vertical positioning assembly inthe set position until the lock is released.
 8. The apparatus of claim1, further comprising a vacuum system for drawing a vacuum through thedischarge-conduit array when the carriage is in the second position. 9.The apparatus of claim 1, wherein the first position is an elevatedposition and the second position is a lowered position.
 10. Anapparatus, comprising: a platform having a first treatment station and asecond treatment station, the first treatment station including a holderfor securing a first receiving array of receiving wells or receivingholes, and the second treatment station including a holder for securinga second receiving array of receiving wells or receiving holes; acarriage configured to carry a discharge-conduit array comprisingdischarge conduits into a position above the first receiving array atthe first treatment station, and configured to carry thedischarge-conduit array into a position above the second receiving arrayat the second treatment station, the carriage being configured for: (1)movement between the first treatment station and the second treatmentstation; (2) movement at the first treatment station along a first,generally horizontal, axis from a neutral position whereat thedischarge-conduit array and the first receiving array are substantiallyaxially aligned; and (3) second movement at the second treatment stationalong a second, generally horizontal, axis from a neutral positionwhereat the discharge-conduit array and the second receiving array aresubstantially axially aligned; a vertical positioning assembly forsupporting the discharge-conduit array for linear movement at the firsttreatment station along a third, generally vertical, axis between (a) anelevated position whereat the discharge conduits clear the receivingwells or receiving holes of the first receiving array, and (b) a loweredposition whereat the discharge conduits extend down into respectivereceiving wells or receiving holes of the first receiving array; and amanually operable handle connected to the carriage and the verticalpositioning assembly such that a movement of the handle at the firsttreatment station moves the carriage along the first axis, a secondmovement of the handle at the second treatment station moves thecarriage along the second axis, and a third movement of the handle movesthe vertical positioning assembly along at least the third axis.
 11. Theapparatus of claim 10, wherein the handle is configured for pivotalmovement at the first treatment station from a beginning position to aset position, from the set position to an intermediate position, andfrom the intermediate position to a release position.
 12. The apparatusof claim 11, wherein the beginning position is an elevated position, theset position is a depressed position, and the intermediate position isintermediate the beginning position and the set position.
 13. Theapparatus of claim 12, wherein the handle is connected to the carriagesuch that movement of the handle to the release position translates intomovement of the carriage into a transfer position whereat the carriagecan be moved horizontally from the first treatment station to the secondtreatment station.
 14. The apparatus of claim 13, wherein a carriageguide track is provided on the platform for guiding the carriage througha predetermined path from the first treatment station to the secondtreatment station.
 15. The apparatus of claim 10, wherein the firsttreatment station comprises a sample wash station, and the secondtreatment station comprises a sample collection station.
 16. Theapparatus of claim 10, wherein the vertical positioning assemblysupports the discharge-conduit array for movement at the secondtreatment station along a fourth, generally vertical, axis between (d)an elevated position whereat the discharge conduits clear the receivingwells or receiving holes of the second receiving array, and (e) alowered position whereat the discharge conduits extend down intorespective receiving wells or receiving holes of a second receivingarray.
 17. The apparatus of claim 16, wherein the handle is connected tothe carriage and the vertical positioning assembly such that when thecarriage is at the second treatment station movement of the handletranslates into the movement of the vertical positioning assembly alongthe fourth axis.
 18. The apparatus of claim 16, further including areleasable lock wherein when the handle is depressed into the setposition in the first treatment station, in the second treatmentstation, or in both the first treatment station and the second treatmentstation, the releasable lock is adapted to activate and maintain thevertical positioning assembly in the set position until the lock isreleased.